


A Little Observation

by Tobalerone



Category: One Piece
Genre: Ace Lives, Alternate Universe - Canon Divergence, Gen, Luffy saw the future once during marineford he can do it again, Marineford War, Observation Haki
Language: English
Status: Completed
Published: 2019-02-24
Updated: 2019-02-24
Packaged: 2019-11-04 21:28:25
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,255
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17905985
Author URL: https://archiveofourown.org/users/Tobalerone/pseuds/Tobalerone
Summary: A bout of Observation Haki prevents Luffy from having his arms cut off by Mihawk during Marineford. Another bout saves his brother’s life.





	A Little Observation

“—is quite a frightening thought. Your fate has been decided! Regardless of who else gets away, I swear I won’t let the two of you escape! Now, watch what I do!”

“Wait! Luffy!”

It happens too quick. He’s still focused on retrieving Ace’s vivre card, and, by the time he looks up, magma is bubbling a foot away from his face.

Luffy is constantly twisting and ducking and dodging out of the way of attacks he _can’t_ see coming ahead of time, using his insane flexibility to escape strikes that are centimeters away. This should be nothing.

But it isn’t.

His body has been teetering on the edge of complete systematic failure since Impel Down. Iva’s hormones have helped him to push aside his exhaustion, to fight in spite of his debilitating injuries, but they never did heal him, and that is reflected most in his delayed reaction time and reduced speed.

He knows he won’t be able to make it out of the way in time.

And then—Ace is suddenly _there_.

It takes a while for Luffy to process it. To comprehend what his eyes are seeing. His brother, impaled through the chest, _protecting him_. His brother’s vivre card, burning at too rapid a rate.

“Ace…!” Luffy tries to scream, but he feels strangled, short of breath, and it comes out as nothing more than a soft, despaired croak. He can only watch helplessly as Aikanu pulls his arm back, revealing the _hole_ through his brother’s _chest_.

He feels dazed.

Ace falls, Luffy extending his arms to catch him, and—

And then he blinks and, like a bad dream, everything goes away. Ace is not dying in front of him—he’s still in the middle of his standoff against Aikanu.

It’s like earlier, with Hawk-Eye. A crystal-clear vision of something to come—the direct consequences of an action, or inaction, of Luffy’s. Luffy doesn’t know what causes the visions, nor does he know why he’s so sure that they’ll come true unless he does something to prevent them.

But, ultimately, that doesn’t matter. What matters is the fact that, if he doesn’t move, Ace will die. 

 He won’t let that happen.

“Now,” Akainu says, and that’s Luffy’s cue, he’s in second gear before the admiral even finishes his sentence, “watch what I do!”

 “Wait!” Ace cries as Akainu lunges towards Luffy, who’s already moving by the time Ace cries his warning, stooping down to grab the vivre card as he goes. “Luf-!”

He collides into Ace, knocking the breath out of him, and sending them both sprawling onto the ground.

 He’s crying. He can’t help it, not with the image of Ace with a gaping hole in his chest still fresh in his mind. If it weren’t for the solid weight of his brother under him, alive and relatively well, that image would be enough to break him. As it is, Luffy just clutches at Ace and sobs, his brother’s name a mantra, a prayer, on his tongue, even as he’s already dragging the both of them to their feet.

It’s hard. Agonizing, really. He was ready to collapse _before_ forcing his body into second gear, and using it again has really taken the last of his strength from him. He can feel his limbs getting heavier, his movements becoming more sluggish, as the effects wear off. He doesn’t think he’ll be able to use any of his gears again.

Sweat is soaking his hair, his breathing is strained, and his vision is gradually getting blurrier—though that could very well be from the tears.

“Luffy!?” Ace exclaims, confused and concerned, “Why are you crying?”

“You were gonna die!” Luffy wails in response, “I saw it! If I hadn’t moved, you would have died, and it would have been my fault!”

“He saw it…?!” someone nearby echoes, alarmed, “Observation Haki, maybe? Shit—we need to hurry up! Someone, do something about these handcuffs!”

“Luffy, what—” Ace starts, but the admiral doesn’t let him finish.

 “As if I’d let you get away that easily!” Aikanu snarls, turning on heel and relentlessly continuing his pursuit.

Luffy is struggling just to stay on his feet, to stay conscious, more leaning on Ace than really standing, and he can barely keep his eyes open. There’s no way he’ll be able to get both himself and Ace out of the way in time.

He doesn’t have to.

Jimbei intercepts Aikanu’s strike with his bare hands, the force pushing him back towards them, but he holds his ground, temporarily halting Aikanu’s progression.

“Jimbei!” Ace shouts, Luffy echoing him weakly. Ace moves to help, but stops when Luffy buckles without his support. Instead, he grits his teeth and adjusts his grip on Luffy to better support him, glancing anxiously between the admiral and his friend.

 “You’re just delaying the inevitable, Jimbei! Since you were once a Warlord, I bet you know what I’m capable of!”

“I’d be happy to risk my life if I can delay it. I’ve been ready to die from the beginning. Ace! You need to go! Luffy is at his limit. From here on out, it’s your responsibility to get him out of here safely! I’ll hold off Aikanu for as long as I can!”

“You’re not alone, Jimbei!”

And, with that declaration, two men, the sword guy and the bird guy that had helped him earlier, attack Aikanu at once.

 “Marco! Vista!” Ace calls. The two don’t turn to look at him, keeping their attention on the admiral, but that doesn’t stop them from responding.

“You heard him, Ace! We’ll back up Jimbei while you get your little brother out of here. Pops ordered us to keep him safe, too, you know!”

Luffy can see his brother’s conflict in the hard line of his mouth, and the furrow of his brow. He understands. Running away, leaving his crew behind to fight on his behalf—it goes against every instinct Ace has.

Luffy steels himself. If Ace refuses to run, then Luffy won’t leave, either. After what almost just happened… he’s not leaving his brother’s side, not for anything, no matter how exhausted—

Ace turns his back to his crewmates.

It’s the first time Luffy has ever seen him turn away from an opponent. Dumbfounded, he does nothing when Ace grabs him and hoists him onto his back, carrying him piggyback like when they were kids and Luffy would over-exert himself.

The familiarity of the position is enough for Luffy to involuntarily let his guard down. And, once he does that, there’s no going back. Without Luffy actively clinging to every bit of strength he can, forcing himself to last longer, the effects of Iva’s hormones wear off. It’s the most extreme adrenaline crash imaginable—every ache and pain that had been pushed aside is back with a vengeance. Luffy goes boneless, head lulling against Ace’s shoulder blade. He’s too exhausted to so much as lift his head.

 “YOU GUYS BETTER LIVE!” Ace shouts, voice cracking a little, and begins to retreat. The battle behind them is _fierce_ , and though they cannot afford to turn around and watch, they can feel the force of every blow against their backs.

From where he’s pressed up against him, Luffy can feel Ace tense.

“I’m sorry,” Luffy rasps into his ear. It was only a few days ago that he was separated from his own crew, after all. He understands how difficult a decision Ace just made on his behalf.

“You idiot,” Ace replies, “I’m the one who’s sorry.”

**Author's Note:**

> Will I continue this? Maybe, but probably not. Although this AU has potential, I don't really have any more plans for it. Hope you liked it! Comments are always appreciated.


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